1. Field of the Invention
This invention relates to drive control devices in cameras, and more particularly to drive control devices in cameras where the drive stopping operation is controlled by an electromagnet.
2. Description of the Prior Art
The method of drive control of mechanisms in the interior of the camera, for example, a diaphragm mechanism has involved the use of a spring as the drive source, whereby actuation was accomplished through a release button, and to stop further movement, the deflected position of a meter needle or the like was sensed to mechanically effect the stopping operation. In recent years, however, with electronic advances, the electrically operated magnetic devices have found general use in controlling both the actuating and stopping operations. The use of an electromagnet obviates the necessity of using a complicated mechanism, and makes control easy, but it necessitates electrical power. Since cameras are of small size and light weight a battery of small capacity can only be used. This leads to the requirement for limiting the amount of electrical energy needed for the electromagnet to a minimum. In conventional instruments, therefore, in order to make the consumption of electrical energy by the electromagnet as small as possible and, with regard to the electromagnet controlling the stopping operation, in order to effect a response for the initiation of the stopping operation as soon as possible after the control signal from the electrical circuit is received, most efforts have been directed toward reduction of the load on the armature of the electromagnet to as small a value as possible. As a result, the camera suffers a disadvantage in that even a slight shock, for example, will cause accidental displacement of the armature which in turn causes failure to ensure further accurate control.